First, let me start by saying that this drama was less from what I expected it to be.
I mean, Jin Goo's past two works were absolutely gold, and in comparison to them, it just fades away.

The story starts with informing that Gye-hoon has some kind of magical ability that makes him feel the emotions of his twin sister, who was kidnapped as a child. As this is a fantasy drama, I'm not going into any logical explanation of the "Wi-Fi" in question.
Next we were introduced to Da-hyun who is a struggling student.
Both live in the same neighbourhood, where Gye-hoon opened his new restaurant, in effort to fin his kidnapped sister.
Next were the usual bickering and romance moments between the leads.
In the end, the identity of the kidnapper (and also killer) was revealed.
The usual 15th episode breakup, danger to life in 16th episode and patch up in the end.

Now, let me tell about "unanswered questions".
1. We never knew why that person kidnapped and killed his sister. No information on whether he was a psychopath, a rapist or a human trafficker. Nothing, nada. All is left at the imagination of the viewers.
2. The neighbours were made to look suspicious since the start. But at the end, none of those neigbours except one was guilty. So all that "suspicion" thing bore nothing.
3. Da-hyun's mother killed a person as an act of self-defence. The murder was covered by the police. Near the end of the series, she went to the police to confess, but was not arrested. Why? Was it statue of limitation or no body was found or anything else. None of the questions unawsered.

So. overall, this was quite a dull drama. The chemistry between the leads was way unnatural. Half-cooked story was another off thing about this drama. I literally completed the last two episodes in mere half hour by fast forwarding and skipping many unnecessary scenes.
Wouldn't recommend this to anyone unless you have too much of spare time or are a fan of Jin-goo or Moon Ga-young.